Prince George and Princess Charlotte may be royalty but that doesn't stop them from being cheeky kids -- at least according to their great-grandmother, Queen Elizabeth II. The adorable children of the Duke and Duchess of Cambridge reportedly picked a messy and naughty habit that the monarch herself finds amusing. A report by Sunday Express was used for most of the information in this article.

In a new documentary called "The Queen's Green Planet," the Queen gets candid about her close bond with George and Charlotte. The 91-year-old royal, who currently has five great-grandchildren, opened up about what it's like having all those youngsters running around the Buckingham Palace.

A naughty Christmas with the young royals

During the interview, Queen Elizabeth II talks about the royal family's Christmas preparations. Speaking with her senior castle attendant Neil Turner, the monarch admitted that it's the time of the year when Prince George and Princess Charlotte get to show their naughty side, Express reported. According to Turner, his perfect decoration of the Queen's Christmas tree somehow becomes a problem. Apparently, the royal siblings admire the decorations so much that they end up messing it up. "Yes, that is always the problem, as the children love knocking those [decorations] off," Queen Elizabeth II revealed.

And while decorating the royal Christmas tree could be painstakingly difficult, the doting great-grandmother shared that the adorable tots actually enjoy doing it.

In fact, the Queen even suggested that in order to extend the lifespan of the ornaments, it's best if they decorate it themselves. "And the great thing is to make them decorate it, and they’re a bit more careful. It always looks jolly."

Prince George and Princess Charlotte's 'Gan-Gan'

Previously, the Duchess of Cambridge shared that the Queen has always been fond of kids, including her two children.

In an interview, the soon-to-be mother of three revealed that her oldest child, George, calls his great-grandmother "Gan-Gan."

Prince William's wife also noted that Queen Elizabeth II dotes on the youngest royal, adding that she always leaves presents for Prince George and Princess Charlotte whenever they visit her at Buckingham Palace.

There were also claims that the monarch was "really thrilled" when Charlotte was born in May 2015. In fact, Queen Elizabeth II was one of the first to visit the Duke and Duchess of Cambridge as soon as they returned to Kensington Palace from the hospital.

The Queen is now expecting her third great-grandchild from Prince William and Kate Middleton this month.